Thermostat.



Patented A'plf'. 2, |90l.' C. B. BARRETT' & W. vS. W. B-LAKE.

THERMOSTAT.

.(.Lpplication filed Fel?. 6, 1900.)

Patented Apr. 2, I90I. S. W. BLAKE.

no. 670,93l.

C. B. GARRETT &'W

T H E8 l 0 S TAT.

(Application lod Feb. 8, 1900 2 Sheets-Sh-eet 2.

(ND Medial.)-

UNITED Srrfrns Parent Ormes.

CHARLES B. GARRETT AND NILLlAM S. SV. BLAKE, OF MINNEAPOLS,

MINNESOTA, ASSIGNORS OF ONE- PLACE.

THIRD TO MARTIN DYKE, OF SAME THERMOSTAT.

SPECIFICATION forming part 0f Letters Fatemi; No., 670,931., dated April 2, 1901.

Application filed February 6, 1900. Serial No. 4,167. (No model.)

lb afl/U whom it' may concern;

Beit known that we, CHARLES B. GARRETT and `W1LLIAM S. W. BLAKE, citizens of the United States, residing at Minn eapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful 1mprovements in Thermostats; and we do hereby declare the following` to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Our invention has for its object to provide an improved thermostat; and to this end it consists of the novel devices and combinations of devices hereinafterdescribed, and defined in the claims.

The invention is illustrated in the accompanying drawings, wherein like characters indicate like parts throughout the several views.

Figure 1 is a horizontal section taken centrally through the preferred form of our improved thermostat. Figs. 2 and 3 are plan views showing` the two principal sections of the thermostat looking at both of the same from their inner sides, the same beingturned in opposite directions. Fig. 4: is a detail of a handpiece for use in setting the thermostat. Fig. 5 is a View corresponding to Fig. 1, but illustrating almodified construction; and Fig. 6 is a horizontal section showing still another modified construction.

Referring first to the preferred construction illustrated in Fig. l, the numerals 1 and 2 indicate a pair of annular sections, which are preferably of porcelain, being preferably held together by two or more screws 3.

The numerals 4 and 5 indicate a pair of metal circuitterminals or Contact pieces, from which, as shown, circuit-wires 6 and 7 respectively lead. The said terminals e and 5 are shown as held to the porcelain section l by screws or bolts 8, and the member fi, as shown, is offset within a recess 1fL of said section 1, being` at its inner end of disk-like form, while the member 5 terminates at its inner end in a cap or cup-like section 9, having an inturned sleeve portion 10, which is preferably square or angular in cross-section, for a purpose which will presently appear.

The numeral 11 indicates a contact plunger or bolt provided with a square or angular portion 11, that fits and works within the inturned sleeve 10 of the terminal 5 and terminates at its inner end in a contact-head 12. At its outerend the bolt or plunger 11 is provided with external screw-threads 13 and with internal screw-threads 14. A nut 15 is when the device is set screwed onto the threads 13. 'j

To set the device, a fusible stop, as shown, in the nature of a washer, (indicated at 16,) is placed on the outer end of the bolt or plu nger 11 between the nut 15 and the adjacent head of the cup 9 of the circuit-terminal 5. This fusible washer holds the head 1:2 of the bolt 11 out of contact with the disk-like head of the circuit-terminal d, and thus normally the circuit is broken at the thermostat. A. coiled spring 17, which, as shown, is placed around the bolt l1 and is compressed between the bolt-head 12 and the bottom of the cup 9, puts the bolt 11 under strain to move inward.

The fusible stop or washer 16 may be made of any suitable fusible material which under ordinary temperatures has suflcient solidity to resist the tension of the spring 17. le contemplate the use of sealing-wax, rosin, or compositions thereof; but composite metals of sufficiently low fusibility lmay be employed for the purpose.

The thermostat above described is what would be termed an open-circuit thermostat, for the reason that the circuit is thereby normally broken. As shown and preferred, an insulating spacing-ring 18 is placed between the inner portions of the circuit-terminals i and 5.

When the fusible stop or washer 16 is melted by the action of heat thereon, the spring 17 will force inward the contact bolt or plunger 11, and its head 12 will be forced against and make contact with the adjacent portion of the circuit-terminal 4f, and as the said bolt has continuons contact with the sleeve portion 10 of the circuit-terminal 5 the circuit will of course be closed through the thermostat. v

Fig. 5 illustrates a construction of the thermostat designed as a closed-circuit thermo IOO stat, and the construction thereof is the same as that illustrated in Fig. 1, with the following exception: The head 12 of the contact 'bolt or plunger ll is preferably made wider than in the formerconstruction, and an insulatingpiece 19 is placed on the depressed disk-like inner extremity of the circuitterminal t for engagement with the said head 12 when the bolt is thrown inward to prevent closing of the circuit. Normally the head 12 is held outward and in engagement with a contact-finger 2O of the terminal 4. iVith this construction the circuit through the thermostat is normally closed and the circuit is broken by the inward movement of the contact bolt or plunger 11, which carries the head 12n ont of contact with the finger 20, and thus breaks the circuit. Of course in this construction, as in the prior construction, the fusible washer or stop 1G holds the plunger or bolt- 1l outward or in its normal position. After the thermostat has been thrown into action a person may readily tell by an inspection of the fusible plug or washer whether the thermostat is operated by heat acting to fuse the washer or whether the plug was broken mechanically by accident or design.

For use in connection with the thermostats above described l preferably employ a hooked handpiece 21, which is screw-threaded at its end 22 to adapt it to be screwed into the internal threads 1e of the contact plungers or bolts 11. When the handpiece 21 is thus applied to one of the contact bolts or plungers 11, the same may be drawn downward or outward against its spring 17, and while it is thus drawn the nut 15 and the washer or stop 16 maybe removed and a new washer or stop 16 substituted for the one removed. The stem of the handpiece 21 is of such diameter that the nuts 15 and washers 1b' may be slipped in either direction from end to end over the same. This is important, as it permits the washers or fusible stops 16 to be replaced while the handpiece is applied to draw the contact bolt or plunger downward, The engagement of the squared or angular portion 11n of the contact-bolt 11 with the correspondingly-formed sleeve 10 holds said bolt against rotation as the nut 15 is turned.

Another very important feature, which is common to both of the forms ofthermostats above described, will now be considered.

The insulating-ring 1S, which spaces apart the enlarged inner extremities of the circuitterminals L1 and 5, forms an air-tight joint between them, and the fusible washer or stop 16 forms an air-tight joint between the bulged portion of the terminal 5 and the nut 15. The nut 15 being tightly screwed onto the threads 13 forms an air-tight joint with the bolt or plunger 11. lf found desirable, the so-called washer 1G might be coated with an adhesive material before it is placed in working position,or it might be slightlyheated on its faces to insure an extremely tight joint.

ln the above manner the internal parts of the thermostat, including` the parts which make and break the circuit by contact and L-epara tion, are incased within an air-tight and d ustproof housing. This prevents dust from getting into the thermostat and onto the contacting portions, and it also prevents the said parts from corroding or becoming oxidized. The above construction we consider broadly new.

ln the construction illustrated in Fig. (i, indicates a support, of insulatingmaterial, to which a pair of circuit-termi nais, in the form of '[iat springs 2-1, are secured by binding-screws 25, to which the line-wires 2U are attached. One of the members 2-1- has a tubular lateral extension or sleeve 27, and the other has aconical metallic extension 28, which is adapted to telescope into the sleeve 27, but is, when the thermostatis set or inoperative, held from such telescoping movement by a ring or body 29, of sealing-wax or other fusible material, which is secured within the outer end of the sleeve 27. lf the sleeve 27 be of metal or of conducting material, then it is necessary that the fusible ring or stop 29 be a non-conductor of electricity, so that the circuit through the thermostat will be normally broken. thcn the ring 29 is fused, it will permit the inner end of the conical extension 2S of the one spring-terminal 211 to be thrown into contact with the other member of the said spring contacts or terminals 24E. Thus it will be noted that the points of contact between the contacting portions of the two circnit-terminals4 or members of the thermostat are remote from the point where the fusible stop is applied. This is lan important feature and is a feature in common with the construction above described.

The uses of a thermostat are well understood and are too numerous to justify an attempt at their enumeration. A thermostat such as is the subject-matter of this application is especially adapted for use in connection with automatic fire alarm and extinguishing systems.

lll/'hat we claim, and desire to secure by Letters Patent of the United States, is as follows:

1. In a thermostat, the combination with a pair of circuit-terminals, of a plunger or bolt movable through one of said terminals, and held against rotation with respect thereto, a spring applied to force said plunger or bolt in one direction, a nut on the end of said plunger, and a perforated fusible washer applied on said plunger between said. n ut and the circuit-terminal in which said plunger is mounted, which washer may be slipped onto said plunger and into working position only when said nut is removed from the said plunger, substantially as described.

2. In a thermostat, the combination with the circuit-terminals 4- and 5, the latter having the bulged portion E) and angular sleeve 10, of the contact-bolt 11 having the head 12, with angular portion 11 and nut 15, the spring IIO 17 applied to said bolt, and the fusible washer 16 applied on the said bolt between the nut 15 aud the bulged portion 9, substantially as described.

3. In a thermostat, the combination with a contact bolt or plunger and a fusible stop for holding` the same inoperative, of a handpiece detaehably securable to said plu nger, and adapted to hold the same inoperative while said stop is removed, substantially as described.

4L. In a thermostat, the combination With a pair of circuit-terminals, of a spring-pressed contact bolt or plunger mounted in one of the said terminals, a nut screw-threaded on one end of said bolt, a fusible Washer adapted to be placed on said bolt inward of said nut, and the handpiece 2l adapted to be screwed into the end of the said bolt, to move the same against its spring, the said liandpieee being of such size that the said nut and fusible Washer may be passed over the same, substantialbT as described.

in testimony whereof we aiiix our signatures in presence of two witnesses.

CHARLES B. GARRETT. WILLIAM S. l/V. BLAKE. Witnesses:

HARRY KILGORE, F. D. MERCHANT. 

